Method of drying coal and like fuels



Patented July 31, 1928.

HANS FLEISSNER, OF LEOBEN, AUSTRIA.

METHOD OI DRYING COAL AND LIKE FUELS.

No Drawing. Application filed April 25, 1927, Serial No. 188,594, and in Austria May 14, 1926.

This invention relates to an improved method of drying coal and like fuels.

It frequently happens that fuels, particularly brown-coal containing of water, fall to pieces. In order to prevent the. fuel from falling to pieces during the drying operation it has been proposed to heat the fuel to the drying temperature, e. g., to about 100 degrees centigrade, in the presence of steam or by means of steam, in order to destroy its colloidal character, and subsequently reduce gradually the pressure of the steam in order to effect a slow drying without that the fuel falls to pieces.

In the assay-office good results have been obtained with this known method. However this known method did not prove a success as soon as tests had been carried out on a large scale, because by heating the fuel to 100 degrees centigrade the colloidal character of some parts of the fuel to be dried had not been positively destroyed and the subsequent drying by reducing the pressure of the steam takes up much time, as it has to be carried out slowly.

Now tests carried out on a large scale have shown. that the drying operation can be carried out more quickly in accordance with an increased temperature to which the coal is heated before the actual drying by sub- 4 jecting it to the treatment by steam. The

process .is carried out at a quick pace in case the temperature. is considerably above 100 degrees-Celsius, for instance between 120 C. and 180 C. Already a considerable part of the water is removed from the coal during the cutting -off of the steam. The subsequent drying by reducing the steam-pressure calls for a much shorter time than without the previous heating ,to a higher temperature, and the reduction of the partial steam-pressure may be accomplished by the application of cold air, in order to obtain a considerable reduction of the water contained in the coal.

In case of employing these high temperatures the walls of the arrangements employed therefor have to be of considerable strength, but 1n spite of this the process according to the present invention possesses 'reat advantages over the known processesl great economical working will resultparticularly when employing a number of boila large quantity same from falling to first heatmg the fuel in saturated steam unwhich are arranged behind one another der pressure, to a temperature which is conslderably -hi her than the drying temperaconnectedwith each other in such a ture, and su sequently drying by reducing the partial pressure of the steam in order to prevent the fuel from falling to pieces and provlde for a quick drying.

2. Method of drying coal and like fuels of a colloidal character so as to prevent the same from falling to pieces, consisting in first heating the fuel in saturated steam under pressure, to a temperature which is considerably higher than the drying temperature, and suisequentlv rapidly cooling the steam to reduce the partial pressure thereof 7 in order to prevent the fuel from falling to pieces and provide for a quickclrying.

3. A method of drying coal and like fuels of a. colloidal character as claimed in claim 2 in which the rapid cooling of the steam is effected by blasts of cold air.

4. Method of drying materials of a collo1dal character so as to prevent the same from falling .to pieces, consisting in first heating the material in a saturated vapor of the liquid to be removed under pressure, to a temperature which is considerably higher than the vaporizing of the liquid to be removed and subsequently rapidly cooling the saturated vapor to reduce the partial pressure thereof in order to prevent the fuel from falling to pieces and provide fora quick drying.

In testimony whereof I alfix my signature.

HANS FLEISSNER. 

